The present invention relates to a gas-laser arrangement, with a gaseous medium being optically pumped using an electric discharge, for example in a discharge chamber.
Arrangements and methods for optically pumping gas lasers are already known. As summarized, for example, in "Zeitschrift Laser and Optoelektronik", Vol. 16, p. 105 (1984), gaseous or vaporous dimers may be optically pumped with laser light that is irradiated from the outside into a gas cell. As shown by the example of an atomic iodine laser, a gas laser may also be pumped by an incoherent light source. The realization of a continuous-wave or cw-laser pumped with an arc lamp is presented in IEEE J. of Quantum Electronics, Vol. QE 20, p. 1187 (1984); the description of a pulsed iodine laser pumped by a flash lamp is given in the Springer Series Opt. Sci., Vol. 9, p. 142 (1978). The discharge tubes, in which the light sources are operated, can have a cylindrical or helical shape; in any case, they form a physical wall between the discharge and the gas volume.
From the specialized literature, for example from Z. Physik, Vol. 216, p. 33 (1968), and from Proc. IEEE, Vol. PS 1, p. 3 (1973), it can be seen that only a small amount of the radiation which is emitted in the interior of an arc discharge or a spark discharge escapes the discharge. Depending on the type of gas and the temperature in the discharge tube, the larger part of the radiation, especially the resonance radiation, is reabsorbed in the colder boundary layer of the discharge. In the case of rare gases and many other gases, the resonance radiation is emitted in the vacuum-uv (vuv) spectral region and is therefore reabsorbed, if not in the gas, in any case by the tube wall.
As a consequence, up to now vuv-radiation from discharges is not available for optical pumping. But vuv-radiation would be useful for many excitation processes, for example for the excitation of rare gases in order to operate a cw-excimer laser. Up to now the resonance radiation in spectral regions of longer wavelength can also not be practically used for efficient optical pumping since the major part of such radiation is reabsorbed in the interior of the light source.
It is therefore an object of the present invention to provide a gas-laser arrangement by means of which optical gain can be produced in a gaseous medium along a straight column with pump light of high intensity down to the vuv-region.